1. Field of the Invention
The present invention relates to a method of storing a solid chlorinating agent which tends to generate gases, such as chlorine gas and nitrogen chloride gas, upon decomposition during storage.
2. Brief Description of the Invention
Solid chlorinating agents have been widely employed for practical use in various fields as disinfectants, germicides, bleaching agents and the like. Such solid chlorinating agents include chlorinated isocyanuric acid such as trichloroisocyanuric acid, dichloroisocyanuric acid, anhydride, monohydrate or dihydrate of sodium or potassium dichloroisocyanurate and a mixture thereof, and high grade bleaching powder, as well as a composition thereof incorporated with auxiliary agents. The chlorinating agents have been used in various forms, such as powders, granules, grains, pellets and tablets.
The solid chlorinating agents are usually stored and transported in closed packing containers which are made of such materials as paper, plastics and metals. Since the solid chlorinating agents are often stored for a prolonged period of time, e.g., up to 1 to 2 years, after manufacture before they are actually used on site, noxious gases could be generated upon decomposition of the solid chlorinating agents and the generated gases may exert undesirable influences, causing in extreme cases dangerous incidents. For example, such noxious gases may cause label information inked on a container to become unclear or faded away completely. The gas generation also may cause the corrosion of packing materials or the breakdown of containers per se due to an increase in internal pressure therein. In addition, the gases generated by decomposition may give unpleasant feeling to workers upon opening of a packing container or during use on the site and could even be harmful to the human body. It is therefore strongly desired to solve the above problems.
Many attempts have been made so far to overcome the said problems involved in the generation of the noxious gases. One attempt is to decrease the water content in the product, thereby preventing the generation of the gases during storage. However, it is almost practically impossible to commercially produce products virtually free from water. It also have been attempted to store the product under a circumstance where the moisture contained in the outside atmosphere is completely blocked. However, even in cases where a container composed of a metallic material capable of completely blocking the outside moisture are used, the metallic material may be subject to corrosion and the container per se may be deformed or even broken during long periods of storage due to increase in the internal pressure of the container caused by the gradual accumulation of the decomposed gases. A further attempt also has been made to prepare the product in granular or tablet form, so as to reduce the specific surface area of the products and, as a consequence, to reduce the generation of the gases. The method, however, gives only unsatisfactory results for a storage over an extended period of time.
In U.S. Pat. No. 4,334,610 is proposed a method in which a porous gas-permeable bag charged with a compound, such as calcium oxide, sodium phosphate, ferrous oxide and magnesium oxide, is placed in a container employed for the storage of solid chlorinating agents. By this method, however, there is a room for more suppressing, the generation of chlorine, nitrogen chloride and oxidized chlorine gases and the available chlorine contained in the chlorinating agents tends to be rather decomposed in undesirably large amounts.
U.S. Pat. No. 4,389,325 proposes a method for suppressing the generation of chlorine gas by the use of a certain synthetic zeolite, which is mainly consisted of alumino silicate. However, according to tests carried out by the inventors, no marked effects could be obtained by this method (see Comparative Examples 1, 5 and 9 described hereinafter).